Nat Technical Reference; Nat Definitions - ZyXEL Communications P-793H v3 User Manual

Figure 56 Network > NAT > ALG
The following table describes the fields in this screen.
Table 32 Network > NAT > ALG
LABEL
Enable SIP ALG
Apply
Reset

9.6 NAT Technical Reference

This chapter contains more information regarding NAT.

9.6.1 NAT Definitions

Inside/outside denotes where a host is located relative to the P-79X, for example, the computers of
your subscribers are the inside hosts, while the web servers on the Internet are the outside hosts.
Global/local denotes the IP address of a host in a packet as the packet traverses a router, for
example, the local address refers to the IP address of a host when the packet is in the local
network, while the global address refers to the IP address of the host when the same packet is
traveling in the WAN side.
Note that inside/outside refers to the location of a host, while global/local refers to the IP address
of a host used in a packet. Thus, an inside local address (ILA) is the IP address of an inside host in
a packet when the packet is still in the local network, while an inside global address (IGA) is the IP
address of the same inside host when the packet is on the WAN side. The following table
summarizes this information.
Table 33 NAT Definitions
ITEM
Inside
Outside
Local
Global
NAT never changes the IP address (either local or global) of an outside host.
Chapter 9 Network Address Translation (NAT)
DESCRIPTION
Select this to change the private ports or IP in SIP messages so that the VoIP
client behind the P-79X can be found in RTP traffic.
Click this to save your changes.
Click this to restore your previously saved settings.
DESCRIPTION
This refers to the host on the LAN.
This refers to the host on the WAN.
This refers to the packet address (source or destination) as the packet travels on the
LAN.
This refers to the packet address (source or destination) as the packet travels on the
WAN.
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